The present invention is related to a printer which performs printing with a print head, a carriage supporting structure and a head assembly incorporated in the printer.
Generally speaking, in a printer, a printing operation is carried out by such a manner that either a carriage which mounts thereon a print head or a head assembly is relatively transported with respect to recording paper, while the head assembly is arranged by both a print head and a peripheral component thereof.
As disclosed in, for example, Japanese Patent Publication No. 11-192719A, a conventional carriage supporting structure for supporting and transporting a carriage mounted on such a printer employs such a structure that the carriage is supported on a carriage guide shaft so as to be transported. FIG. 1 is a side view showing the conventional carriage supporting structure with employment such a carriage guide shaft.
In FIG. 1, a carriage 51 comprises a bearing portion 64 in which a cylindrical-shaped hole is formed. A carriage guide shaft 65 made of a metal comprises a cylindrical shape which may be fitted to the hole of the bearing portion 64. The carriage 51 is supported by a carriage guide shaft 65 which is penetrated through the hole of the bearing portion 64.
The carriage 51 also has a belt receiving portion 63, while an endless belt (not shown) is fixed on this belt receiving portion 63. Then, drive force which is produced by rotations of a drive source such as a motor is transferred via this endless belt to the belt receiving portion 63, so that the carriage 51 is moved in the reciprocation manner along a main scanning direction.
Also, as described above, the carriage guide shaft 65 supports the carriage 51 in order that the carriage 51 can be moved in the reciprocation manner along the main scanning direction. Furthermore, this carriage guide shaft 65 regulates an interval between a print head 62 mounted on the carriage 51 and a recording surface of recording paper xe2x80x9cPxe2x80x9d which is transported while being slidably contacted to a platen 52. This interval is a so-called xe2x80x9cpaper gapxe2x80x9d (will be simply referred to as a xe2x80x9cgapxe2x80x9d hereinafter).
On the other hand, while the carriage 51 has a guide portion 66, the carriage 51 is supported by this guide portion 66 with respect to a frame member 8 of the printer main body, so that a parallel degree of the head face of the print head 62 may be regulated.
As is well known in the art, the above-described gap xe2x80x9cPGxe2x80x9d may constitute the very important factor capable of greatly applying influences to printing qualities. Only when this gap xe2x80x9cPGxe2x80x9d is slightly changed from a defined gap value, the printing qualities would be largely changed. The conventional carriage supporting structure in which the carriage 51 is supported on the carriage guide shaft 65 comprises high gap precision, and thus, the gap xe2x80x9cPGxe2x80x9d is maintained substantially constant. Accordingly, there is a very small risk that the printing qualities are deteriorated since the gap xe2x80x9cPGxe2x80x9d is slightly changed from the defined gap value. As a consequence, very recently, this conventional carriage supporting structure could be widely employed even in printers capable of executing high-quality printing operations.
On the other hand, there is such a trend that printers are manufactured in lower cost. Considering price aspects of these low-cost printers, such an idea that carriage supporting structures manufactured in lower cost rather than such a carriage supporting structure constructed of the carriage guide shaft 65 are mounted on printers may effectively reduce resultant cost of these printers.
However, such a low-cost carriage supporting structure capable of maintaining the same level of the gap precision as that of the above-described conventional carriage supporting structure constituted by the carriage guide shaft 65 is not present in the carriage supporting structures known in this technical field.
Besides, in color printers, very high precision as to paper feeding mechanisms is necessarily required, so that these paper feeding mechanisms must be provided with complex constructions. In connection with these complex constructions, a total number of assembling steps for the respective components is also necessarily increased.
As a method capable of reducing total manufacturing steps, the following method has been considered. That is, while components are separately assembled to both a main frame and a sub-frame of a printer, these main frame and sub-frame are finally assembled to each other outside a printing area so as to reduce a total assembling step number of these components with respect to each of manufacturing lines for these frames, so that positional precision among these components may be increased.
However, in the case that such an assembling method is employed, an ink jet recording printer may have the following risk, while this ink jet recording printer requires a provision of a space (namely, home position) used for a maintenance purpose of a print head outside a printing area. That is, a carriage guide is flexed downwardly due to the own weight of the print head traveled to the home position side, so that a gap xe2x80x9cPGxe2x80x9d may be changed.
Furthermore, in such a printer that the print head 62 is mounted on the carriage 51, the travel precision and the response precision of the carriage 51 are adversely influenced, depending upon the assembling precision of these components. In particular, there is a risk that these adverse influences may cause more or less problems when image qualities of color printers are improved.
Furthermore, in such a case that this sort of carriage 51 must be replaced by new one, the following cumbersome works are necessarily required. That is, while the carriage 51 is dismounted from the carriage guide shaft 65 which has been previously dismounted from the printer main body, a new carriage 51 is penetrated thereto, and thereafter, this carriage guide shaft 65 should be assembled to the printer main body. In such a case that a play is produced between the print head 62 and the carriage 51, there is probability that the printing operation by the printer cannot be carried out under normal condition.
A first object of the present invention is to provide such a carriage supporting structure of a printer, while this carriage supporting structure can be made in low cost and can maintain a similar level of gap precision to that of a carriage supporting structure with employment of a carriage guide shaft.
A second object of the present invention is to provide a carriage supporting structure in which a gap is not changed due to the own weight of a print head, while a total number of manufacturing steps can be reduced.
A third object of the present invention is to provide such a head assembly capable of being a printer without employing a carriage, while superior drive operations and superior response characteristics can be maintained.
A fourth object of the present invention is to provide a head assembly capable of being mounted without dismounting a carriage guide shaft, and furthermore, capable of achieving high-precision printing operation.
A fifth object of the present invention is to provide such a printer equipped with the carriage supporting structure having the above-explained various merits.
A sixth object of the present invention is to provide a printer equipped with the head assembly having the above-described various merits.
In order to achieve the above objects, according to the present invention, there is provided a printer, in which printing is performed on a recording medium which is transported in a first direction, comprising:
a carriage, reciprocately moved in a second direction which is perpendicular to the first direction;
a print head, mounted on the carriage, the print head having a head face;
a first frame, placed in a first side of the print head; and
a first guide plate, extending in the second direction, which includes:
a first portion, provided as a part of the first frame so as to extend in a third direction which is orthogonal to both of the first direction and the second direction;
a second portion, continued from the first portion so as to extend in the first direction, the second portion supporting the carriage so as to define a distance between the head face and the recording medium; and
a third portion, continued from the second portion so as to extend in a fourth direction opposite to the third direction.
When one sheet of flat metal plate is bent by applying bending force to this metal plate along only one direction, this metal sheet may have two faces with different bending angles from each other. Such a metal plate will be flexed under such a condition that this metal plate is curved along a direction opposite to this bending direction. Therefore, subsequently, any one of these two faces is bent in such a manner that bending force is applied to this selected face along a direction opposite to that of the firstly-applied bending force, and thus, a sectional view of this face becomes a crank shape. As a result, a center face (above-described second portion) of the three faces which are formed by executing the above-explained two bending processes may become such a face having a very high flatness, since the flection of this plate which is caused by applying the bending force along two opposite directions is canceled.
It should be understood that the above-described crank-shaped bending process indicates such a condition that the flection caused by the bending process is canceled by applying the bending force along the opposite directions. As a consequence, this crank-shaped bending process may cover not only such a case that the angles of the first and third portions in the above-described structure with respect to the second portion are substantially equal to the right angle, but also may cover another case that these angles become acute angles, or obtuse angles.
As a consequence, the second portion for supporting the carriage as a so-called xe2x80x9cgap defining facexe2x80x9d, namely the face for defining the distance between the head face of the print head and the recording surface of the recording paper corresponds to such a face having the high flatness, whose flection caused by the bending process may be canceled by applying thereto the bending force along the two opposite directions. As a result, the gap definition can be realized in high precision. Then, the first guide plate containing this second portion is arranged with the first frame in an integral manner, whereas the components of the carriage guide shaft mounting apparatus such as the carriage guide shaft and the bush can be reduced, so that the cost of this printer can be reduced. As a consequence, it is possible to provide such a low-cost carriage supporting structure with maintaining the same level of the gap precision as that of the carriage supporting structure constructed of the carriage guide shaft.
Preferably, the carriage is provided with a first guide member which is slid on a first face of the second portion of the first guide plate when the carriage moves in the second direction.
In accordance with this structure, even when the carriage is transported, the gap defined between the head face of the print head and the recording surface of the recording paper can be regulated in high precision.
Here, it is preferable that the first guide member is slid on a line situated at a substantially center of the second portion of the first guide plate in the first direction.
Since this position corresponds to such a portion having an especially high flatness within the second portion, and also, the first guide member is slidably contacted to this portion, the gap can be regulated in higher precision.
Preferably, either one of the first portion and the third portion of the first guide plate defines a position of the carriage in the first direction.
As previously described, the second portion of the first guide plate may become such a face having the very high flatness, the flection of which caused by the bending process is canceled by applying the bending force along the two opposite directions. Then, both the first portion and the third portion may become such faces having relatively high flatness, because of this very high flatness. Therefore, the position of the carriage along the first direction (namely, sub-scanning direction) can be defined in higher precision.
Here, it is preferable that the carriage is provided with a second guide member which grips either one of the first portion and the third portion of the first guide plate, so that the second guide member is slid thereon when the carriage moves in the second direction.
In accordance with this structure, the position of the carriage along the first direction can be defined in high precision.
Preferably, the carriage is provided with a third guide member which is slid on a second face of the second portion of the first guide plate when the carriage moves in the second direction. Here, the second face is an opposite face of the first face.
In accordance with this structure, since the first guide plate is sandwiched by both the first guide member and the third guide member, the position of the carriage along the third direction (namely, upper/lower directions) can be defined. As a consequence, it is possible to avoid such a phenomenon that the gap is changed due to vibrations applied to the carriage, and thus, the printing qualities are deteriorated.
Preferably, the printer further comprising:
a second frame, placed in a second side of the print head which is opposite side of the first side;
a second guide plate, extending in the second direction, which includes:
a fourth portion, provided as a part of the second frame so as to extend in the third direction;
a fifth portion, continued from the fourth portion so as to extend in the first direction, the fifth portion supporting the carriage so as to define the distance between the head face and the recording medium; and
a sixth portion, continued from the fifth portion so as to extend in the fourth direction.
In accordance with this structure, since the gap is regulated by the two faces as to the second portion of the first guide plate and the fifth portion of the second guide plate, the parallel degree defined between the head face of the print head and the recording surface of the recording paper may also be regulated in addition to the gap.
Here, it is preferable that the carriage is provided with a fourth guide member which is slid on the fifth portion of the second guide plate when the carriage moves in the second direction.
In accordance with this structure, even when the carriage is moved, both the distance and the parallel degree between the head face of the print head and the recording surface of the recording paper can be regulated in high precision.
According to the present invention, there is also provided a printer, in which printing is performed on a recording medium which is transported in a first direction, comprising:
a carriage, on which a print head is mounted, reciprocately moved in a second direction which is perpendicular to the first direction;
a recording region, in which the print head performs printing;
a home position, provided in one of both sides of the recording region in the second direction, at which the carriage is placed when the print head does not perform printing;
a first frame, including:
a carriage guide, extending in the second direction from the recording region to the home position such that the carriage moves therealong; and
supporting legs, extending downwards from both side end portions of the carriage guide; and
a second frame, including:
first positioning members, which define positions of the supporting legs in the first direction;
second positioning members, which define positions of the supporting legs in the second direction;
third positioning members, which define positions of the supporting legs in a third direction which is orthogonal to both of the first direction and the second direction; and
a supporting base, which supports at least a bottom portion of one supporting leg situated in the home position.
In accordance with this structure, even when the respective components are independently assembled to the different frame members of the printer, since these frames are positioned with respect to the main scanning direction, the sub-scanning direction, and the upper/lower direction (namely, first to third directions respectively), not only the positioning precision among these components can be maintained in high degrees, but also the printing precision achieved by the print head can be maintained in high degrees even in such a type of printer that the print head is moved to the home position side for maintenance purpose. That is, since the carriage guide projected to the home position side is supported by the supporting base, such a phenomenon that the carriage guide is flexed downwardly due to the own weight of this print head can be suppressed, and also the gap can be continuously and correctly held.
According to the present invention, there is also provided a printer, in which printing is performed on a recording medium which is transported in a first direction, comprising:
a first guide plate, extending in a second direction which is perpendicular to the first direction;
a looped belt member;
a drive motor, which circulating the looped belt member in the second direction;
a head assembly, including:
a print head;
a belt holder, at which a part of the looped belt is fixed; and
a first guided portion, provided in a first side of the print head, and slid on the first guide plate in accordance with the circulation of the looped belt member.
In accordance with this structure, since the head assembly can be mounted on the printer without using the carriage, not only the structure of this head assembly can be made simple, but also there is no play produced among the components. Therefore, the drive characteristic of the head assembly can be largely improved, and furthermore, the response characteristic thereof can be extremely improved.
Preferably, the printer further comprises a second guide plate placed in a second side of the print head, which is an opposite side of the first side, so as to extend in the second direction. Here, the head assembly includes a second guided portion slid on the second guide plate in accordance with the circulation of the looped guide member.
In accordance with this structure, the head assembly can be supported under more stable condition.
Preferably, the first guided member is slidably held on the first guide plate while defining a position of the print head in the first direction. Here, the head assembly includes a third guided portion slidably held on the first guide plate while defining a position of the print head in a third direction which is orthogonal to both of the first direction and the second direction.
In accordance with this structure, such a cumbersome work is no longer required. That is, the carriage guide shaft and the like are dismounted from the printer main body. Moreover, the print head itself can be assembled on the carriage guide plate. As a consequence, the works for assembling the print head to the printer main body can be largely made simple, and at the same time, the scanning precision thereof can be extremely improved. In addition, a total number of these structural components can be greatly reduced.